This application pertains to plastic pigment semi-gloss enamel latex paint and relates to the commonly assigned U.S. Pat. No. 4,069,186 pertaining to latex paint containing solid plastic pigment particles.
Prior to plastic pigment latex paints as disclosed in U.S. Pat. No. 4,069,186, conventional high quality latex paint compositions contained opacifying pigments such as TiO.sub.2 and non-opacifying pigments such as inerts or extenders to produced high quality paint films which can be easily washed or scrubbed without ruining the paint film surface. Semi-gloss and hard surface enamel latex paints have been compounded at a very low pigment-volume-content (PVC) in the range of about 20% PVC. The hard surface enamel finish is obtained by the high level of film-forming binder which necessarily is at an 80% level on a dry solids volume basis to correspond with a 20% PVC. The high binder content is far beyond that required to fully encapsulate the dry pigments and hence the excess binder appears to gravitate to the film surface and provide a hard semi-gloss enamel surface. Providing a semi-gloss latex paint is in itself a recent advancement since latex paints are normally flat.
Commonly assigned U.S. Pat. No. 4,069,186 discloses an improved latex paint composition utilizing solid non-film-forming plastic particles in combination with opacifying pigments to provide a latex paint composition having a pigment-volume-content (PVC) greater than the critical-PVC to provide substantially improved opacified paint films at a wide range of PVC levels above the critical-PVC. The dried paint films have excellent high opacity coincident with high enamel holdout and low surface porosity to produce dry paint films which maintain excellent film integrity and remain resistant to surface deterioration as well as being easy to scrub. A low-gloss latex paint film can be achieved at high PVCs by utilizing plastic pigment non-film-forming polymeric particles at very high PVCs of about 70% PVC.
It now has been found that excellent semi-gloss paint film havig good wet adhesion and exhibiting hard enamel surfaces can be produced with plastic pigment at PVC levels below critical-PVC but at surprisingly high PVCs in the range of about 35% to 40% PVC by utilizing small size plastic pigment particles containing minor amounts of copolymerized acrylic or methacrylic acid. High PVC paints compounded closer to the critical PVC can be obtained providing a substantial improvement over conventional latex enamels compounded at low PVC levels of about 20% PVC. The certain carboxyl containing plastic pigment is utilized in combination with opacifying pigment and small particle size film forming latex binder to produce an excellent, high quality, hard enamel surface paint film. A further advantage of this invention is that wet adhesion is surprisingly obtained with vinyl copolymer binders which ordinarily do not exhibit good wet adhesion in conventional latex paints. These and other advantages will become more apparent by referring to the detailed description and illustrative examples.